Frozen beverage or food product dispensing machines are known in the art that utilize a freezing cylinder for producing a slush beverage or frozen food product. An evaporator coil is wrapped around the exterior of the cylinder for cooling the contents thereof. A scraper mechanism extends along the central axis of the cylinder and is rotated to scrape thin iced or frozen layers of the beverage or food product from the internal surface of the cylinder. Such an approach is therefore useful for the production carbonated and noncarbonated flavored slush ice drinks as well as ice creams and frozen yogurts.
A drawback to theses machines is the fact that the scraper mechanism inherently requires a shaft portion thereof to extend through a cylinder end for connection to a drive motor, thereby requiring a dynamic seal. This requirement stems from the fact that the drive mechanism is exterior of the cylinder and can not come into direct contact with the food product therein. Naturally, such seals are subject to wear and consequent leaking, especially where the beverage contents are under pressure, as is the case for a frozen carbonated beverage. Major service problems with such machines are related to failed or leaking scraper shaft seals. Accordingly, it would be very desirable to be able to eliminate such seals, yet have a scraper drive mechanism that does not create food compatibility/contact problems, and that has sufficient strength to operate the scraper against the considerable resistance it encounters when producing the desired frozen food product.